Technical Abstract:
Although the use of hyperaccumulators to phytoextract heavy metals from soil is a cost effective and efficacious technology, perceived risks associated with phytoextraction have slowed its implementation. Because hyperaccumulators are most often non-indigenous to the site of use, concerns related to invasiveness have been raised. On non-metal enriched soil, we believe the potential for "escape" beyond the original area of planting is minimal. Hyperaccumulators have an inherently high requirement for metals and thus fail to thrive on soils with "normal" concentrations of metals. Thus, spread of hyperaccumulators is anticipated only on those soils enriched with metals. Invasiveness must be a concern on mineralized soils with high metal content. Hyperaccumulators surviving on mineralized soils could disrupt indigenous ecosystem. Pollen from hyperaccumulators can travel with wind and insects for many kilometers. Concerns of wildlife poisoning have also been raised anytime hyperaccumulators are grown in the field. Observations in the field have suggested that Alyssum species high in Ni are unpalatable. When GMO hyperaccumulators are grown beyond confinement, additional concerns are raised related to the fate of the transgenes. However, existing concerns with non-GMO hyperaccumulators combined with concerns associated with transgenes suggests that the public may be skeptical and demand a very critical review prior to release and use of GMO hyperaccumulators in the field.